Activation of petroleum acid sludge coke for preferential paraffin adsorptioon



A PROPANE E o E I J o I E I j 4. I "N V ETHYLENE Z 5 I 9 W I I a l g l l k In 2 i Q l i 1 I l I l o I l I l I t I 0 1o 50 40 e0 '70 50 so A911] 30, 1957 w. A. KONRAD 7 2,790,511

ACTIVATION OF PETROLEUM ACID SLUDGE COKE FOR PREFERENTIAL PARAFFIN ADSCRPTION Filed May 11, 1953 3 Sheets-Sheet 1 RELATIONSHIP OF ADsoIz TIvE CAPACITY JAN'D PRODUCT Y ELD QF-STEAM-ACTIVATED ACID SLLJDGE COKE YI ELID WT. "/o

F IGM-l CJELZ. Cam a. Konrad Unverzbor b Qbborrieg April 30, 1957 KONRAD 2,790,511

W. A. ACTIVATION OF PETROLEUM ACID SLUDGE COKE FOR PREFERENTIAL PARAFFIN ABSORPTION Filed May 11, 1953 3 Sheets-Sheet 2 COZ+CQ.+ H STEAM Coma STORAGE 5 l I m- T: 2 -CYLONE I LJ FLlJl-D v QEACTOK STEAM- G ACTIVATED CARBON F 1: c; 2 l

COT LL Lam G- Konrad Gnverzbor b8 C ltbor'rzes ACTIVATION OF PETROLEUM ACID SLUDGE COKE FOR PREFERENTIAL PARAFFIN AD- SORPTION William A. Konrad, Springfield, N. 1., assignor to Esso Research and Engineering Company, a corporation of Delaware Application May 11, 1953, Serial No. 354,224

2 Claims. (Cl. 183114.2)

This invention relates to the preparation of an attrition-resistant activated carbon from petroleum acid sludge particularly for selective adsorption ofpropane in a mixture with ethylene.

States Patent 2,790,511 Patented Apr. 30, 1957 to be partially burned with air until the coke is given The present application is a' continuation-in-part of application, Serial Number 120,975, filed October 12, 1949, now abandoned, wherein is described more generally the preparation of various activated carbons from petroleum acid sludge.

It has generally been known that activated carbons produced from various cokes or chars have the property of adsorbing gaseous hydrocarbons and various col oring bodies. There are numerous activated carbons having widely varying properties depending on the precise manner in which they are formed, even when formed from the same raw materials.

In accordance with the present invention an outstanding-activated carbon is made for the preferential adsorption of propane in the presence of ethylene from a petroleum acid sludge coke that is prepared in a particular manner from the sludge and is then activated to a critical degree with reference to yield of activated carbon for obtaining a particularly high adsoiptive capacity attendant with high selectivity for propane and high attrition resistance. 7 v

The petroleum acid sludges are well known to be produced as a result of various petroleum refining operations, particularly the sulfuric acid treatment of gaso line, lubricating oils, and higher-boiling petroleum distillates, such as phenol extracted oils from which the so-cal-led white oils are' produced by treatment with fuming sulfuric acid or S03. The resulting acid layers from the above kinds of treatments vary in character. depending upon the severity of the acid treatments, but, in general, the acid layers consist in carbonaceous residues admixed with unreacted sulfuric acids, sulfonic acids, other sulfur derivatives and water from which a tarry residue called a sludge is obtained upon the settling of the acid layer. The petroleum acid sludge coke which is employed in this invention is prepared from the sludge as follows:

The tarry sludge is introduced into a decomposition zone simultaneously with a stream of preheated coke particles previously obtained from acid sludge. In the decomposition zone the liquid sludge is carbonized very rapidly by contact with the coke particles preheated to temperatures in the range of 800 F. to 1500 F. The weight ratio of the hot coke particles to the sludge varies from 2:1 to about 6:1 so that in a very short space of time, generally less than 10 minutes, the completecarbonization of the sludge on the seed coke takes place. During the carbonization of the sludge on the seed coke in the decomposition zone, volatile matter present in the sludge is distilled, and the mass of coke having a freshly carbonized sludge deposit thereon becomes cooled down to temperatures in the rangeof 300 F. to 750 F. The cooled coke can then be withdrawn from the sludge decomposition zone.

a temperature in the range of 800 F. to 1500 F. preferably 1000 F. to 1200 F. in a short period of time, generally 5 to 25 minutes. It is this thus heated coke which is then used as the preformed and preheated seed coke for depositing sludge thereon in the described decomposition zone.

The balance of the coke removed from the decomposition zone is 'the'material which is then used for activation. It canbe screened or classified to obtain a desired size, for example, a particle size in the range of 10 or 14 to 20 mesh. The particles larger than 10 mesh size may be com-minuted by grinding and screening. This raw coke has a bulk density of about 48 lbs/cu. ft.

Studies on the preparation of carbon adsorbents have shown that the adsorptive capacity of the carbon increases as the "yield-level is decreased, even as the yield level is decreased to below 40 wt. percent. However, the activated product of the present invention which meets the critical requirements of high selectivity for propane in the presence of ethylene, and high attrition resistance, commensurate with good adsorptive capacity can only be prepared in the yield range of 50 to 60 wt. percent.

As shown in Fig. 1, the activity (adsorptive capacity) for both propane and ethylene tends to increase at the sacrifice of activating carbon yield from the acid sludge coke. The carbons or chars of highest activity occur in the very low yield ranges, i. e. 10 to 30 weight percent yield. These carbons or chars cannot be employed economically as adsorbents'in a commercial type of operation, especially one in which the adsorbent is fluidized or moved in a stream countercurrent to a mixture of propane and ethylene which is to be separated, on acf, count of the inferior physical characteristics of these carbons obtained at these low yields.

For example, the bulk density (grams per cc.) and resistance to attrition ofthese low yield carbons are very poor. These carbons are light and fluffy and if used in a selective adsorption process would require the circulation of prohibitively large volumes of carbon. When the activated carbon yield from the acid sludge coke is decreased to belowwt. percent, the bulk density decreases and the attrition rate rises rapidly. I The abrupt rise in attrition rate relative to a commercial cocoanut shell carbon when the yield is decreased to below 50 wt. percent is shown in the following table:

TABLE I Efiec't of activated char yield from acid sludge carbonized on coke Yield (wt. percent). 100 60 55 50 49 40 20 Attrition ratenni 0. 75 0. 1.3 1.3 1.3 1.5 2.1 3.9

The representative data points in the above table illus trate the importance of avoiding a high attrition rate byyield from going to substantially TABLE II Figure 2 represents a diagrammatic sketch of a typical fluid reactor for the steam activation of the acid sludge coke. Coke of proper particle size is led from storage vessel 1 via pipe 2 to the tapered reactor 3, wherein the coke builds up a bed designated by the upper level L. If desired an inert gas may be introduced to pipe 2 via line 4 for the purpose of fluidizing the coke. This gas may be Hz, CO2, CO, steam or inert mixtures of the same but preferably steam or the off-gases from the Selectivity f the activated sludge coke (separation factor) see Table III Yield (Wt. percent) 100 86 60 57 56 55 54 52 48 44 Separation factor 0.13 6.39 11.19 11.42 11.47 13.34 12. 91 12.51 10.07 9 71 The foregoing table clearly shows that there is an steam activation process, e. g. that stream emerging from abrupt peak in the improved separation factor when the the process via line 5. activated carbon yield from the described acid sludge The k i i the reaction Zone f reactor 3 is Coke is dbfihitely in range of 50 9 f heated to the desired temperature, say 1350 F. to 1800 ggfiggfi i ii tili ig rg oi fi io q a "S deslred actlvated F. but suitable means, such as hot gas, by steam, or by s heat exchange means not shown, e. g., hot coils within the Studies with carbons re ared according to the recess of this invention show hai the minimum adsorbe iit rate bed 35 slectntcal F i 3 g g of the in pounds, carbon, per cubic foot for separating equio f 2 S 15.1mm i mto t e tapered p molal ethylene-propane mixture into 95% pure products i 0 e Wager. Vla hnes 6 m amoullts and at Yelocl' increases with increasing yield of the Carbon from the UGSPI'BVIOUSIY indicated. When operating batchwise the Steam activation process Due to the efiect of the attainment of the carbon yield level 18 indicated by checkbulk density the minimum volumetric adsorbent rate 40 P the total volume of gas P1Oduced during thb activa- (cu. ft. carbon/cu. ft. feed) goes through a pronounced hon Process, of y actual measurement 0f the depth of minimum at approximately 50-55% yield, then increases bed remaining With the aid of pressure p placed at at yields above and below this level. The minimum intervals along the vertical axis of the reactor. ifiumber of stages required for the separation of propane When operating continuously other factors such as rom ethylene is also at this peak level in the range of rate of burning, bed depth, velocity and contact time Percent yield of actiyjrlted Fafbon from h must be correlated to determine the point at which the described sludge coke. These relationships are shown in desired yield level is attained T 1 ;:i i-re a wh ch S eaming or act g o Gas resulting from the steam-contacting, including 50 H2, CO2, CO and excess steam, pass upwardly into cythe sludge Coke 18 c.amed 9 Is IndePeHdFnflY clone separator 7 in which carbon particles are extracted cal. The rate at which a given yield of an activated carth f d th a f th t bon is obtained from the acid sludge coke depends upon mm an e lemammg piisses 6 the nature of the coke, the temperature of steam, the hne A pornon of the s i If deslredfimay be length of the steaming, the amount of steam (wt. steam/ r5 cycled to employed for fiuldlllng k being charged wt. carbon) and the superficial velocity of the steam. through hne Practical steam temperatures are within the range of Actlvated Carbon is Wlthdrawh from the reactor by 1350 to 1800 F., preferably about l400 to 1650 F. P p 8 Controlled y Valve The length of steaming may be in the range of from The activated carbon formed from the described type 10 minutes t0 3 hours, p b l y 20 minutes to 1 hour- 60 of acid sludge coke possesses the highly desirable adsorp- The amoupt of stegam usgd IS 21 th ia g l -3 tion selectivity and capacity for separating propane from gr e fi ir i ll to 0 ;:/sect?ir rabli la fo llgii.l c. ethylene methane and l f when the yield of While it is possible to employ temperatures outside the activated carbon formed is critically controlled to come above range, in the range stated, easier and more efficient Wlthm the g of 50 to 60 f percent control f the activation is possible, The Critical The following Table Ill contains data on the selectivity trol factor in the activation is the precise yield level. and p y of the activated carbons p y in the The steaming of the coke may be carried out in any separation of ethylene-propane gaseous mixtures. These Suitable manner but Preferably in a reactor in which carbons were obtained by steaming the described acid Steam is Passed upwardly through a fluidized bed of the sludge coke under the conditions set forth in the table.

coke particles at such a rate that the bed is kept in a continuously fluid state resembling a boiling liquid. A fixed bed activator is suitable also. Due to the thorough mixing encountered in the fluid bed reactor, a product of greater homogeneity of chemical, physical and adsorption properties is obtained.

The cokes were obtained by calcining of sludges from the treatment of petroleum fractions with sulfuric acid, the calcining process having been carried out in the manner outlined, i. e., the sludge was-deposited as a coating on the hot seed coke and rapidly decomposed thereon.

TABLE III Selectivity Steaming W.IW./(lb. Yield, Adsorption (77 F.1 Temp, F Time steam/lb. Wt., Atm.) (Milllmols/Om.)

(Min) carbon Percent Alpha Gas Comp. at

Equilibrium 01H; Cal 120 7. 8 52 3. 55 4. 86 12. 51 74.8% 01H in vapor. 30 2. 56 3. 52 4. 87 12. 39 76.8% 02H; invapor. 16 1 1 54 3. 60 4. 95 12. 00 75.0% (32H; in vapor. 60 1. 24 79 2. 84 2. 75 6. 25 62.0% (32H; in vapor. 40 3. 24 44 3 50 5. 59 9.71 70.0% (32H; invapor.

'Alpha= selectivity faetor-%X% A== Concentration of more adsorbable propane component in adsorbate. B= Concentration of less adsorbable ethylene component in adsorbate. B= Concentration of less adsorbable ethylene component in unadsorbed gas. A Concentration of more adsorbable propane component in unadsorbed gas.

The activated carbon prepared by this invention is particularly applicable to the separation and recovery of ethylene from petroleum refinery cracking process gases, such as may contain methane, ethane, in addition to ethylene and propane. The propane and ethylene may be present in catalytic cracking gases or thermal cracking gases.

What is claimed is:

l. A process for preparing activated carbon adapted to adsorb propane selectively in a mixture with ethylene, which consists essentially in introducing into a decomposition zone a stream of preheated petroleum acid sludge coke particles preheated to a temperature of 1000 F. to 1200 F. as seed coke particles, simultaneously introducing into said decomposition zone one part by weight of petroleum acid sludge from each 2 to 6 parts by weight of said seed coke particles entering the decomposition zone to deposit said sludge on said seed coke at 1000 F. to 1200 F., carbonizing the sludge deposited on the seed coke in the decomposition zone while distilling volatile matter from the thus deposited sludge undergoing carbonization and simultaneously cooling the coke having the freshly carbonized sludge deposit thereon down to a temperature in the range of 300 to 750 F. as the coke travels through the decomposition zone in less than 10 minutes, removing the thus cooled coke particles with freshly carbonized sludge deposit thereon from said decomposition zone, thereafter treating the resulting coke particles removed from said decomposition zone with steam at 1400 to 1650 F. until between 40 and 50 weight percent of the coke particles treated is reacted with steam to give a yield of to weight percent of the activated carbon based on the weight of the steam treated coke particles.

2. In a process of selectively adsorbing propane from a mixture thereof with ethylene, the improvement which comprises contacting the mixture of propane and ethylene with an activated carbon prepared by a combination of steps which consists essentially in decomposing petroleum acid sludge deposited in a ratio of 1 part by weight of sludge per 2 to 6 parts by weight of hot coke on preformed petroleum acid sludge coke particles preheated to temperatures of l000 to 1200 F., the deposited sludge being carbonized and simultaneously cooled on said preheated coke particles to temperatures in the range of 300 to 750 F. in less than 10 minutes, and the resulting coke particles having the thus decomposed sludge thereon being treated with steam at 1350 to 1800 F. until a yield of 50 to 60 weight percent of activated carbon is obtained.

References Cited in the file of this patent UNITED STATES PATENTS 2,393,214 Andrews Jan. 15, 1946 2,412,667 Arveson Dec. 17, 1946 2,586,889 Archibald et al. Feb. 26, 1952 2,635,709 Vesterdal et al. Apr. 21, 1953 OTHER REFERENCES Hypersorption Process for Separation of Light Gases by Clyde Berg, A. I. ch. E. Transactions, vol. 42, N0. 4, pages 665-680. 

1. A PROCESS FOR PREPARING ACITIVATED CARBON ADAPTED TO ADSORB PROPANE SELECTIVELY IN A MIXTURE WITH ETHYLENE, WHICH CONSISTING ESSENTIALLY IN TRODUCING INTO A DECOMPOSITION ZONE A STREAM OF PREHEATED PETROLEUM ACID SLUDGE COKE PARTICLES PREHEATED TO A TEMPERATURE OF 100*F. TO 1200*F. AS SEED COKE PARTICLES, SIMULTANEOUSLY INTRODUCING INTO SAID DECOMPOSITION ZONE ONE PART BY WEIGHT OF PETROLEUM ACID SLUDGE FROM EACH 2 TO 6 PARTS BY WEIGH OF SAID SEED COKE PARTICLES ENTERING THE DECOMPOSITION ZONE TO DEPOSIT SAID SLUDGE ON SAID SEED COKE AT 100*F. TO 1200*F., CARBONIZING THE SLUDGE DEPOSITED ON THE SEED COKE IN TEH DECOMPOSITION ZONE WHILE DISTILLING VOLATILE MATTER FORM THE THUS DEPOSITED SLUDGE UNDERGOING CARBONIZATON AND SIMULTANEOUSLY COOLING THE COKE HAVING THE FRESHLY CARBONIZED SLUDGE DEPOSIT THEREON DOWN TO A TEMPERATURE IN THE RANGE OF 300* TO 750*F. AS THE COKE TRAVELS THROUGH THE DECOMPOSITION ZONE IN LESS THAN 10 MINUTES, REMOVING THE THUS COOLED COKE PARTICLES WITH FRESHLY CARBONIZED SLUDGE DEPOSIT THEREON FROM SAID DECOMPOSITION ZONE, THEREAFTER TREATING THE RESULTING COKE PARTICLES REMOVED FROM SAID DECOMPOSITION ZONE WITH STEAM AT 1400* TO 1650*F. UNTIL BETWEEN 40 AND 50 WEIGHT PERCENT OF THE COKE PARTICLES TREATED IS REACTED WITH STEAM TO GIVE YIELD OF 50 TO 60 WEIGHT PERCENT OF THE ACTIVATED CARBON BASED ON THE WEIGHT OF THE STEAM TREATED COKE PARTICLES. 